Usc2013 Anesthesia For The Obese Patient

Front 1

Overweight is defined as

Back 1

Having more body fat than what is considered to be optimally healthy.

Front 2

What is "Optimal Health" defined as

Back 2

The ability to live life with robust vitality free of troubling symptoms and chronic disease.

To enjoy physical, mental, emotional, and spiritual health.

Front 3

What is ideal body weight?

Back 3

IBW is a standardized weight as related to height

MALE
*IBW (kg) = 22 x height in meters squared
* IBW (kg) = Ht cm - 100
* IBW (lbs) = 105 + 6 lbs for every inch over 5 ft.

FEMALE
* IBW (kg) = 20 x height in meters squared
* IBW (kg) = Ht cm - 105
* IBW (lbs) = 100 + 5 lbs for every inch over 5 ft.

Front 4

Obesity is classified as

Back 4

Obesity =

IBW > 20%
BMI > 30

Front 5

Morbid Obesity is classified as

Back 5

IBW > 2x
> 45kg or 100 #'s of IBW

Front 6

The World Health Organization defines obesity as

Back 6

The World Health organization defines obesity as an abnormally high percentage of body fat.

Front 7

The CDC and NIH define overweight as ___________. They define obesity as ____________.

Back 7

The CDC and NIH define overweight as

a BMI of 25-29.9 .

Obesity is defined as:

a BMI of 30 or greater.

Front 8

BMI =

Back 8

BMI = kg/(height in meters)^2

Front 9

Where do most of the obese population live in the US?

Back 9

In the south/ southeast.

Front 10

True or false

Obese patients that have fat deposits around their middle have no greater risk of heart disease than patients who have fat deposits on their thighs.

Back 10

True

Front 11

Physiologic Changes Associated with Obesity

Back 11

1) Increased O2 Consumption
2) Increased CO2 Production
3) Decreased chest wall compliance
4) Restrictive lung disease pattern
5) Decreased FRC, VC. Decreased ERV, IRV. RV remains the same
6) Hypoxemia
7) Intrapulmonary Shunt increases
8) V/Q ratio is decreased.
9) Obstructive Sleep Apnea
10) Obesity Hypoventilation Syndrome (OHS)

Front 12

Normal O2 consumption is _____ mL/min. In an obese patient, O2 consumption increases by ____%.

Back 12

Normal O2 consumption is 250 mL/min. In an obese patient, O2 consumption increases by 40%.

Front 13

Why is CO2 production increased in the obese patient?

Back 13

Metabolic rate increases with body weight.

Front 14

Do obese patients lose residual volume?

Back 14

No. They lose ERV and IRV.

Front 15

Why can't obese patients lie supine?

Back 15

It decreases their reserve volume to breathe even more due to gravity.

Front 16

Why do obese patients have hypoxemia?

Back 16

Hypoventilation and low V/Q ratio.

Front 17

What compensatory mechanisms attempt to compensate for hypoxemia in the obese patient?

Back 17

Increased cardiac output

Hypoxic Pulmonary Vasoconstriction and Increase PVR, causing PULMONARY HTN.

Front 18

Pulmonary HTN in the obese is a result of

Back 18

Hypoxic Pulmonary Vasoconstriction.

Front 19

What does being obese do to your shunt ratio?

Back 19

It increases. Because there is decreased ventilation.

Qs/Qt = (CcO2 - CaO2)/ (CcO2 - CvO2)

Front 20

What is the name of the questionaire used to diagnose OSA

Back 20

BANG questionnaire.

Front 21

What is

Obesity-hypoventilation syndrome (aka: Pickwickian Syndrome)?

Back 21

* A complication w/ extreme or severe obesity
* Hypercapnia: PaCO2> 45
* Daytime Hypercapnia and hypoxia as well as nite-time.
* More likely to have Pulmonary HTN, Hypervolemia, cor pulmonale
* These people rely more on their hypoxic drive to breathe.
* These people have a high sensitivity to opiods and rely more on their hypoxic drives to breathe.
* They are usually on Bipap at home.
* These people develop CHF and right sided heart failure.
* The people get pulmonary hypertension. Then they get right sided heart failure due to the pulmonary hypertension.
* Somnulence and OSA occurs - bipap at home.
* They have increased blood lipids which predipose them to cardovascular disease.

Front 22

Why do the obese have a high sensitivity to opiods and sedatives?

Back 22

They rely more on their hypoxic drive to breathe.

Front 23

What are the cardiovascular consequences of obesity?

Back 23

--> Increased circulating blood volume to try to compensate for the hypoxemia.
--> Increased metabolic demand
--> Increased Cardiac Output predominantly with increases in stroke volume and a normal heart rate with increased body fat mass.
--> Increased left ventricular filling pressure (HTN) and volume shifts the Frank Starling Curve to the left.
--> Over time, this dilates the cardiac chambers.
--> CHF is seen in 10% of these patients due to increased volume and HTN.

Also...

* Right sided heart failure secondary to pulmonary hypertension.
* Pulmonary hypertension due to HPV and increased cardiac output.

Front 24

What are the physiologic cardiovascular consequences of obesity?

Back 24

* Increased pro-thrombotic factors, fibrinogen, factor VII and vWF. This increases the risk of venous thromboembolism and PE.

* Endothelial disruption (in BV's) decreasing nitric oxide avaliability which leads to increased vascular resistance and HTN.

Front 25

Why do the obese have an increased risk of aspiration?

Back 25

Fat pushes up on stomach and decreases esophageal tone.

Front 26

True or false

Being obese delays your gastric emptying time.

Back 26

False

There is no difference in gastric emptying time, gastric volume, or pH between the obese and the non obese.

However, most obese pts have diabetes, and it is the diabetes that delays gastric emptying times.

Front 27

What causes insulin resistant diabetes in the obese?

Back 27

Adipose tissue Hypoxia (ATH) inhibits glucose uptake in adipocytes.

Front 28

Why do obese patients get liver cirrhosis

Back 28

They get fatty liver disease. The fat destroys the liver.

Front 29

List all the comorbities of Obesity

Back 29

HTN
--> Endothelial cell disruption causes a loss of NO and you lose some vasodilation.

DYSRHYTMIAS

MI
--> Hypoxemia, Increased CO

PULMONARY EDEMA
--> Increased Blood Volume

STROKE
--> atherosclerosis causes

INSULIN DEPENDENT DIABETES
--> Hypoxic Adipose Tissue causes decreased insulin uptake by adipocytes

VENTRAL & HIATAL HERNIA
--> Due to increased abdominal pressure

HYPOTHYROIDISM

FATTY LIVER
--> Cholelithiasis

THROMBO-EMBOLISM
--> Due to atherosclerosis.

Front 30

What are some common surgical procedures for obese patients?

Back 30

HERNIA REPAIRS

CHOLECYSTECTOMY
--> Gall Bladder Dysfunction common

IRRIGATION AND DEBRIDEMENT OF WOUNDS

GASTRIC PROCEDURES
--> Banding - put bands on gastrum to decrease stomach size
--> Sleeve - cut out more than half of your stomach and leave what looks like just a sleeve.
--> Rose -
--> Bypass (Roux-en-Y)

Front 31

What is the danger in having obese pts that are hypertensive before sx?

Back 31

The HTN will make the obese patient crash even more.

Front 32

What types of tests to obese pts need preop?

Back 32

Stress Test
EKG
Echo
BP

Cardiovascular disease may be disguised...need to look for it.

Front 33

What type of Pre-op Labs and Tests to Obese patients need?

Back 33

* Electrolytes
* Glucose (many are diabetic)
* CBC
* BUN
---> Kidneys take a beating w/ obesity due to the triglycerides and diabetes.
* Creatinine
* Liver Studies
---> Non alcoholic fatty liver disease (NAFLD)

RESPIRATORY TESTS
--> Smoker?
--> Sleep Apnea?
--> PFT
--> Baseline ABG
--> CXR - look to see just how high up is the diaphragm?

Front 34

Complete Airway Assessment of an obese patient involves...

Back 34

--> Positioning on the OR table
--> Bougie
--> Video laryngoscope
--> Awake fiberoptic - may be necessary in extremely large patients.
---> Use pillows to support body and line up airway.

Front 35

What are some preop meds for the obese?

Back 35

* Antisialogogues
* H-2 Antagonists
* Reglan - increases esophageal sphincter tone
* Bicitra - Increases gastric pH (alkalyzes it)
* Benzodiazepine
* Narcotic

Front 36

What meds should you be careful giving to your obese pt from pre-op to OR?

Back 36

Benzo's

Narcotics

You could easily lose your airway and would have no way to intubate.

Front 37

How can you widen out the bed for an obese patient?

Back 37

With "sleds"

Front 38

What is an ideal position for obese patients on the way to sx?

Back 38

Reverse Trendelenburg. 15 deg tilt

NEVER LAY THEM FLAT

Front 39

What are some risks and benefits of general and regional anesthesia for fat people:

Back 39

* Able to provide oxygenation and ventilation with sedation

* Potential Airway Difficulties

* Emergence

* Risk of Aspiration

* Pain management w/o having to use additional sedation.

Front 40

What are some risks and benefits with regional anesthesia for obese patients:

Back 40

* Maybe very challenging to perform. Landmarks are difficult to palpate and the needle might not be long enough to get to where it needs to go.

* Patient required sedation with regional may be inadequate as patient is uncomfortable

* Patient unable to tolerate position and maintain effective cardio-respiratory function with or without sedation.

* Obese patient may crash quicker with a local anesthetic because intravascular volume is more depleted.

* Give fluids with a regional block.

* Blocks are great for post op pain management in obese pts because pain meds would suppress their RR.

Front 41

How long should you preoxygenate obese patients

Back 41

3-4 minute 100% O2 is more effective than 4- maximal breathes.

Front 42

Where should you put EKG leads on fat people?

Back 42

In a place where the fat doesn't move so they will pick up.

Front 43

Why should you consider an RSI?

Back 43

Two Reasons

1) Most obese patients are diabetic and therefore have slow gastric emptying.

2) They have a decreased FRC adn will therefore become hypoxic sooner so you have to hurry.

Front 44

Should you use an ETT or an LMA with obese pts?

Back 44

ETT

LMA can cause aspiration.

Front 45

Ketamine as an induction agent can cause ____ in the obese.

Back 45

Ketamine as an induction agent can cause HTN in the obese.

Front 46

Propofol as an induction agent can cause _____ in the obese.

Back 46

Propofol as an induction agent can cause HOTN in the obese.

Front 47

What should be the duration of action of NMB's in obese pts?

Back 47

They should be short to intermediate acting.

Because they can get stuck in the fat and have a prolonged duration.

Front 48

What type of inhalation agent should obese pts get?

Back 48

Desflurane - quick on and quick off because it has a LOW lipid solubility.

Front 49

What is a bad side effect of Desflurane?

Back 49

It's an airway irritant.

Can also cause tachycardia

It's also the most expensive gas!!

Front 50

If you use Iso or sevo on an obese pt, when should you start turning it off?

Back 50

Start turning it down 15-20 min before the end of the case. Especially with iso.

Front 51

What is an ideal narcotic to give an obese patient during sx?

Back 51

Remi-fentanyl

It's quick on and quick off. Wont' get stuck in fat.

Avoid using long acting narcotics morphine, dilaudid.

Front 52

What are some non-narcotic analgesics that you can give to obese patients.

Back 52

* Local field block
* N-SAIDS
* Alpha 2 Agonist - Precedex
* Toradol
* Ofirmev

Front 53

How can you prevent/ treat Post Op Nausea and Vomiting

Back 53

* Ondansetron (Zofran) given 30 min before the end of induction.

* Decadron (be careful giving this in diabetic pts - can cause hyperglycemia).

* Avoid phenergan because it can have a sedative like affect.

Front 54

Why is DVT prophylaxis important in obese pts?

Back 54

They have disruption of the endothelial lining, prediposing them to the factors that cause blood clotting.

Front 55

How do you emerge an obese pt from anesthesia?

Back 55

* Suction them well.
* Give reversal agent
* Agent off. Put pt on 100% O2
* May need to recruit alveoli: Use 3-5 manual breathes, 12-15 cc/kg with 1-2 second holds.
* Bed slight reverse trendelenburg
* Patient fully awake
* Sustained head lift for 5 seconds.

Front 56

With a train of four of 4 twitches and sustained tetanus how many of your receptors are still blocked?

Back 56

50-70%

Front 57

What is a sign of adequate reversal from an NMB?

Back 57

Sustained head lift for 5 seconds.

Front 58

Why don't you give 100% O2 during the entire case?

Back 58

It will wash out the nitrogen and cause atelectasis.

Front 59

Why types of pain meds do you give obese pt post op?

Back 59

*Non-narcotic analgesics.
* Local anesthetic blocks also work.
* PCA pumps - reduce the risk of respiratory depression with large boluses of pain meds IV. Pain med is given at a nice slow basal rate.

* Bolusing from PCA should be prohibitted!!!

Front 60

How can you decrease the risk of infection, embolism, and resp fail post op in obese pts?

Back 60

Early ambulation!!!

Front 61

How should you transfer your pt to PACU from OR?

Back 61

Head up. 30-45 degrees and on O2.